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Natarajan Perumal, Caroline Manicam, Matthias Steinicke, Alexandra Tschäbunin, Maya Scieranski, Norbert Pfeiffer, Franz H Grus; Application of Targeted Proteomics in Identification of Specific Signature Peptides in Dry Eye Disease: One Step Closer to Personalized Diagnosis?. Invest. Ophthalmol. Vis. Sci. 2017;58(8):796.
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© ARVO (1962-2015); The Authors (2016-present)
Dry eye syndrome (DES) is a common yet debilitating ocular pathology that affects a large population. However, the fundamental etiology underlying this pathology remains elusive. Furthermore, high complexity of tear proteome and limited samples due to low tear protein concentration in DES patients deters detection of specific differentially expressed proteins in individual samples. Therefore, this study endeavored to investigate specific proteome alterations in individual tear samples of DES patients and to determine if any inter-individual variations exist.
Tear samples were collected from healthy subjects (CTRL, n= 18) and aqueous-deficient dry eye patients (DRYaq, n= 18). Samples were analyzed individually employing the targeted mass spectrometry (MS)-based proteomics strategy. The acquired continuum MS spectra were analyzed by MaxQuant computational proteomics platform followed by functional annotation and pathway analyses.
A total of 64 signature peptides representing various protein isoforms, namely PRR4-N1, PRR4-N2, PRR4-N3, S100A8, S100A9, ANXA1 and ANXA2 were identified in the tear samples with less than 1 % false discovery rate. Among these, 23 peptides were significantly (P<0.05) differentially expressed in tears of DRYaq compared to the CTRL. These include increased expression of ALDH3A1, HPX, IGHA1 and S100A9, and decreased expression of LACRT, SERPINB1, PRR4 and LYZ. Noteworthy is that several metabolic, inflammatory and immune processes were highly activated in DRYaq tears. Most importantly, this study has identified variations in the expression levels of specific protein isoforms in different individuals, especially PRR4.
In conclusion, a targeted proteomics strategy was established in this study to identify a high number of specific differentially expressed proteins in individual tear samples of DES patients. This targeted MS strategy is instrumental for unambiguous identification and quantification of specific protein isoforms that cannot be effectively detected by the classical antibody-based methods. Multiplexed measurements of designated proteins based on the signature peptides via targeted strategy have the potential to speed-up expensive and time-consuming DES biomarker discovery in clinical settings, including in larger cohorts of DES patients in a personalized manner.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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